In cellular or wireless communication, modulation used in 4G or LTE systems for example has caused higher levels of saturation in base station power amplifiers than for example 2G modulation. This saturation has meant having to use a cavity filter with a substantial amount of attenuation, such as for example approximately a 30 dB attenuation. Accordingly, this has meant having to use more expensive cavity filters in 4G systems.
Moreover, for a multi-carrier/multi-band application, including without limitation a multi-radio application, such saturation has meant having to use a separate power amplifier and cavity filter path for each band. Along those lines, amplifier saturation rolloff may be too large in some instances to make it practical to have two bands in a same cavity filter envelope.
Hence, it is desirable and useful to provide signal preconditioning prior to input to a power amplifier that overcomes or mitigates one or more of the above-described limitations.